This invention relates to a weighing system, especially a weighing system for small quantities of materials such as vitamins, minerals and drugs.
Apparatus for weighing small quantities of materials presently involves use of a plurality of fixed material containing bins having screw conveyors to advance ingredients from the bins to a weighing U-shaped container or tub. After the desired amount of ingredients is placed in the tub, the tub is inverted to dump it. This system has problems, however.
Specifically, firstly the materials sometimes bridge above and around the conveyor screw so as not to be dispensed as needed. Secondly, the materials, after becoming aerated, sometimes "squirt" out of the discharge end of the screw conveyor rather than flowing smoothly. Thirdly, after the needed quantity of valuable ingredients has been discharged from the individual hopper, some still remains in the hopper and conveyor and must be retrieved somehow before a new ingredient is placed in the hopper. Fourthly, after the ingredients are placed in the weighing tub and the tub is inverted, some ingredients tend to stick to the tub and remain in it, to cause the weighed material to be lacking in that ingredient, and to possibly cause contamination of subsequently weighed ingredients.